Atmospheric and oceanic impacts of Antarctic glaciation across the Eocene-Oligocene transition.

The glaciation of Antarctica at the Eocene-Oligocene transition (approx. 34 million years ago) was a major shift in the Earth's climate system, but the mechanisms that caused the glaciation, and its effects, remain highly debated. A number of recent studies have used coupled atmosphere-ocean climate models to assess the climatic effects of Antarctic glacial inception, with often contrasting results. Here, using the HadCM3L model, we show that the global atmosphere and ocean response to growth of the Antarctic ice sheet is sensitive to subtle variations in palaeogeography, using two reconstructions representing Eocene and Oligocene geological stages. The earlier stage (Eocene; Priabonian), which has a relatively constricted Tasman Seaway, shows a major increase in sea surface temperature over the Pacific sector of the Southern Ocean in response to the ice sheet. This response does not occur for the later stage (Oligocene; Rupelian), which has a more open Tasman Seaway. This difference in temperature response is attributed to reorganization of ocean currents between the stages. Following ice sheet expansion in the earlier stage, the large Ross Sea gyre circulation decreases in size. Stronger zonal flow through the Tasman Seaway allows salinities to increase in the Ross Sea, deep-water formation initiates and multiple feedbacks then occur amplifying the temperature response. This is potentially a model-dependent result, but it highlights the sensitive nature of model simulations to subtle variations in palaeogeography, and highlights the need for coupled ice sheet-climate simulations to properly represent and investigate feedback processes acting on these time scales.

Survey of medical training in cytopathology carried out by the journal Cytopathology.

This report of the Editorial Advisory Board of Cytopathology gives the results of a survey of medical practitioners in cytopathology, which aimed to find out their views on the current situation in undergraduate and postgraduate training in their institutions and countries. The results show that training in cytopathology and histopathology are largely carried out at postgraduate level and tend to be organized nationally rather than locally. Histopathology was regarded as essential for training in cytopathology by 89.5% of respondents and was mandatory according to 83.1%. Mandatory cytopathology sections of histopathology were reported by 67.3% and specific examinations in cytopathology by 55.4%. The main deficiencies in training were due to its variability; there were insufficient numbers of pathologists interested in cytology and a consequent lack of training to a high level of competence. Pathologists without specific training in cytopathology signed out cytology reports according to 54.7% of responses, more often in centres where training was 3-6 months or less duration. Although 92.2% of respondents thought that specialist cytology should not be reported by pathologists without experience in general cytopathology, that practice was reported by 30.9%, more often in centres with small workloads. The survey report recommends that 6-12 months should be dedicated to cytopathology during histopathology training, with optional additional training for those wanting to carry out independent practice in cytopathology. Formal accreditation should be mandatory for independent practice in cytopathology. When necessary, temporary placements to centres of good practice should be available for trainees intending to practise independently in cytopathology. There should be adequate numbers of pathologists trained in cytopathology to a high level of competence; some of their time could be released by training cytotechnologists and trainee pathologists to prescreen cytology slides and assess adequacy of fine-needle aspiration samples when immediate diagnosis was not required. The survey demonstrated a clear need for European and international guidelines for training in cytopathology.

The differential effect of sub-micron level HA aggregates on influenza potency assays.

Influenza vaccines remain the most effective public health measure for the prevention of influenza-related illnesses. The primary immunogen in inactivated influenza vaccines is hemagglutinin (HA), the receptor binding protein of influenza. The concentration of HA during vaccine production and testing is standardized according to the level of antigen as measured by Single Radial Immunodiffusion Assay (SRID). This allows vaccine potency to be controlled such that individuals receive a dose known to provoke a clinically protective immune response. As compared to alternatives, SRID has the advantage of quantifying immunologically relevant forms of HA, but it depends on timely generation of novel reagents for each new vaccine strain. In recent years, a number of alternative assays have been suggested based on either epitope recognition, receptor binding or protection from proteolysis but it is unclear how they relate to vaccine potency in clinical trials. In this report we describe the development of a lectin-based, ELISA-type assay for HA potency and find it provides similar potency estimates to SRID except in the case of a vaccine with aggregated HA and other viral proteins. In that case, SRID predicted the immunologically active HA present and ELISA techniques did not. This difference was due to tested antibodies failing to pull down or bind to the HA present unless particle aggregates were first dissociated. Furthermore, detergent treatment alone was insufficient to complete this dissociation. While others have previously demonstrated that immunocapture-based techniques can misestimate the potency of influenza vaccines depending on the individual antibodies used we demonstrate that in this case the failure was due to an inability of all antibodies to capture HA contained in the aggregated influenza vaccine.

No high Tibetan Plateau until the Neogene.

The Late Paleogene surface height and paleoenvironment for the core area of the Qinghai-Tibetan Plateau (QTP) remain critically unresolved. Here, we report the discovery of the youngest well-preserved fossil palm leaves from Tibet. They were recovered from the Late Paleogene (Chattian), ca. 25.5 ± 0.5 million years, paleolake sediments within the Lunpola Basin (32.033°N, 89.767°E), central QTP at a present elevation of 4655 m. The anatomy of palms renders them intrinsically susceptible to freezing, imposing upper bounds on their latitudinal and altitudinal distribution. Combined with model-determined paleoterrestrial lapse rates, this shows that a high plateau cannot have existed in the core of Tibet in the Paleogene. Instead, a deep paleovalley, whose floor was <2.3 km above mean sea level bounded by (>4 km) high mountain systems, formed a topographically highly varied landscape. This finding challenges prevailing views on tectonic processes, monsoon dynamics, and the evolution of Asian biodiversity.

Improved tumor targeting with chemically cross-linked recombinant antibody fragments.

The construction and use of recombinant chimeric and later fully humanized (CDR-grafted) antibodies to tumor-associated antigens has reduced the immune response generated to these antibodies in clinical studies. However, their long circulating half-life is a disadvantage for tumor imaging and therapy. Fragments such as F(ab')2, Fab', Fv and single chain Fv (scFv) offer faster blood clearance but also lower overall tumor doses. We have examined the tumor targeting of several novel fragments produced by chemical cross-linking of Fab' or scFv to dimeric and trimeric species. To facilitate cross-linking of Fab' fragments, a chimeric B72.3 Fab' fragment has been expressed with a hinge sequence containing a single cysteine residue. B72.3 scFv was also produced with a similar hinge region peptide attached to the COOH terminus to allow cross-linking. These fragments, Fab' delta Cys and scFv' delta Cys were cross-linked with linkers containing two or three maleimide groups to produce dimeric and trimeric molecules with increased avidity for antigen. Cross-linkers were also designed to contain a 12-N-4 macrocycle capable of stable radiolabeling with 90Y. This allowed the production of site-specifically-labeled, fully immunoreactive proteins. Biodistribution studies in the nude mouse LS174T xenograft model with scFv, di-scFv, and tri-scFv demonstrated that these fragments clear extremely rapidly from the circulation and give rise to only low levels of activity accumulated at the tumor. Di-Fab (DFM) and tri-Fab (TFM) however, accumulated relatively high levels of activity at the tumor with high tumor:blood ratios generated, demonstrating improved targeting compared to IgG. cB72.3 90Y-labeled tri-Fab was found not to accumulate in the kidney or the bone, resulting in an attractive antibody fragment for tumor therapy.

Targeting the HA2 subunit of influenza A virus hemagglutinin via CD40L provides universal protection against diverse subtypes.

The influenza viral hemagglutinin (HA) is comprised of two subunits. Current influenza vaccine predominantly induces neutralizing antibodies (Abs) against the HA1 subunit, which is constantly evolving in unpredictable fashion. The other subunit, HA2, however, is highly conserved but largely shielded by the HA head domain. Thus, enhancing immune response against HA2 could potentially elicit broadly inhibitory Abs. We generated a recombinant adenovirus (rAd) encoding secreted fusion protein, consisting of codon-optimized HA2 subunit of influenza A/California/7/2009(H1N1) virus fused to a trimerized form of murine CD40L, and determined its ability of inducing protective immunity upon intranasal administration. We found that mice immunized with this recombinant viral vaccine were completely protected against lethal challenge with divergent influenza A virus subtypes including H1N1, H3N2, and H9N2. Codon-optimization of HA2 as well as the use of CD40L as a targeting ligand/molecular adjuvant were indispensable to enhance HA2-specific mucosal IgA and serum IgG levels. Moreover, induction of HA2-specific T-cell responses was dependent on CD40L, as rAd secreting HA2 subunit without CD40L failed to induce any significant levels of T-cell cytokines. Finally, sera obtained from immunized mice were capable of inhibiting 13 subtypes of influenza A viruses in vitro. These results provide proof of concept for a prototype HA2-based universal influenza vaccine.

Renal biopsy morphology in renal transplantation. A comparative study of the light-microscopic appearances of biopsies from patients treated with cyclosporin A or azathioprine prednisone and antilymphocyte globulin.

Nephrotoxicity is a major side effect of cyclosporin A (CSA) when used in renal transplantation, and the distinction between nephrotoxicity and rejection is important in patient management. One hundred twenty-five renal biopsies were examined from 56 patients entered into a controlled clinical trial aimed at comparing the efficacy of CSA therapy alone to a combination of prednisone, azathioprine, and antilymphocyte globulin (AZA). In order to define the histopathology of rejection and nephrotoxicity, all the biopsies were evaluated in a semiquantitative manner by an observer unaware of the clinical state of the patient. Comparison of the morphological appearances of 32 biopsies from patients on CSA, and 22 biopsies from AZA-treated patients performed during clinically apparent rejection episodes showed that the histological patterns of rejection were the same in both treatment groups. Comparison of the morphological features of 34 biopsies from patients receiving CSA and 13 from patients receiving AZA, performed during prolonged periods of post-transplant renal failure, who eventually recovered on continuation of original therapy, showed that there were no morphological features specific to the CSA-treated group. Five patients on CSA had oliguria which was prolonged by CSA nephrotoxicity. Thirteen biopsies from all five patients showed a diffuse interstitial fibrosis that was peculiar to this group of patients.

Postirradiation recovery of lymphoid cells in the rat.

Whole-body irradiation has been extensively used to ablate immune responsiveness in rodent recipients in adoptive allograft assays. This study was undertaken to determine the relative radioresistance and the tempo of regeneration, following whole-body irradiation, of cells involved in the allograft response. Six distinct cell populations have been identified in the lymphoid tissues of rats subjected to sublethal whole-body irradiation. The relative representation of these subpopulations was significantly different from that in nonirradiated controls. NK cells, macrophages, and plasma cells, which are present in very low numbers in cell suspensions prepared from normal lymphoid tissues, made up a significant proportion of the residual/regenerating population in the tissues of rats recovering from whole-body irradiation. More significantly perhaps, the mature T cell populations showed a significant increase in the T cytotoxic/suppressor to T helper cell ratio. These observations support the suggestion that a number of the cell types within the mixed cell population observed in the rejecting indicator grafts of irradiated recipients in adoptive allograft assays are host derived. The finding that the T cytotoxic/suppressor population is apparently more radioresistant than the T helper population supports a conclusion that graft rejection in irradiated recipients, restored with pure populations of T helper cells, may not be directly mediated by the injected cells but may be the result of collaboration between these and host-derived cytotoxic cell populations.

Identification of the cellular subpopulations infiltrating rejecting cadaver renal allografts. Preponderance of the T4 subset of T cells.

In the rejection response against renal allografts, the relative importance of helper/inducer T cells mediating a delayed-type hypersensitivity response and of T cells with direct cytotoxicity has not been defined. These subpopulations were identified with commercially available monoclonal antibodies and an indirect immunoperoxidase technique in 31 renal biopsies from patients undergoing acute rejection episodes and in 9 rejected nephrectomy specimens. T lymphocytes were the predominant cell population in all biopsies and in 8 of 9 nephrectomies. The T4 helper/inducer subset was equal to, or greater than, the T8 cytotoxic/suppressor subset in 28 of the 31 biopsies and in the 8 nephrectomy specimens that had histological evidence of cellular rejection. T4 lymphocytes were found predominantly in large areas of cellular infiltrate. T8 lymphocytes had a more diffuse interstitial distribution and were a minority of the cells in the large areas of cellular infiltration. These results show that helper/inducer T lymphocytes are often more frequent than cytotoxic/suppressor cells in acute renal allograft rejection in humans and they suggest that helper/inducer T cells may play an important role in the mediation of graft destruction.

Homograft aortic root replacement for destructive prosthetic endocarditis.

Prosthetic aortic valve endocarditis with extensive destruction of the aortic root, annular abscess formation, and left ventriculoaortic discontinuity was seen in 3 patients, with aorta to left atrial fistula formation in 2. Homograft aortic root replacement with use of the anterior mitral leaflet of the aortic root to repair the fistula was used successfully in all 3 patients. Their case reports are discussed to highlight the use of the homograft aortic root in these complicated cases, and to report the occurrence of aorto-left atrial fistula in prosthetic valve endocarditis.

Left atrial reduction for chronic atrial fibrillation associated with mitral valve disease.

Currently available surgical procedures to control chronic atrial fibrillation associated with mitral valvar disease are not always successful. The size of the left atrium is a major factor in the initiation and maintenance of atrial fibrillation. Here we describe a case of ablation of atrial fibrillation with left atrial reduction and pulmonary vein isolation in a patient with mitral valve disease.

Effects of PEEP on cardiovascular dynamics after open-heart surgery: a new postoperative monitoring technique.

The circulatory effects of incremental increases in positive end-expiratory pressure ventilation (PEEP) were assessed on 11 occasions in post-operative cardiac surgical patients by phasic aortic blood flow measurements and high-fidelity pressure recordings from which flow and pressure-flow derivatives of cardiac performance were calculated. At 15 cm H2O PEEP, mean arterial blood pressure was decreased by 10%, stroke volume and cardiac output by 15%, and peak left ventricular power by 21%. Although these indices promptly returned to control levels when PEEP was discontinued, levels of PEEP above 10 cm H2O should be used with caution for this group of patients.

Homograft aortic root replacement to correct infective endocarditis requiring seven open cardiac procedures.

Infective endocarditis, presumably from a septic dental focus, affecting the aortic valve was seen as acute aortic regurgitation in a 20-year-old woman. Seven open cardiac procedures for replacement of the aortic valve and left ventricular outflow tract were performed over the subsequent 6 years. Aortic root replacement using a fresh antibiotic-sterilized homograft was performed as the last definitive operative procedure. This article is presented to highlight (1) the use of homograft aortic root replacement for extensive involvement of aortic valve and left ventricular outflow tract in cases of infective endocarditis and (2) the feasibility of multiple sternal reentries when indicated.

A monitor for the continuous assessment of left ventricular performance after open-heart operations.

A cardiac monitoring system has been developed that incorporated phasic aortic blood flow measurement by an extractable electromagnetic flow probe and high-fidelity arterial blood pressure recordings. Cardiac output, stroke volume, and peak aortic blood flow are measured continuously; using logarithmic amplifiers, the pressure-flow derivatives of left ventricular function, such as cardiac power and stroke work, are obtained beat by beat. This monitor is used to follow the postoperative course of patients undergoing cardiac operations and to evaluate the hemodynamic effect of therapeutic agents.

The value of Medicare statistics in monitoring Pap smear screening. Screening versus non-screening smears: the role of the laboratory.

In November 1991 separate Medicare item numbers were introduced to distinguish screening from non-screening cervical smears for the purposes of monitoring the screening programme. Referring doctors are now expected to indicate the appropriate item number on the request form accompanying the Pap smear. To test compliance with this requirement, we examined 1000 consecutive request forms for cervical smears received in August 1993. We found that 22.7% had no item number indicated and that for a further 10.4% the item number given appeared to be incorrect. As the account issued by the laboratory must show an item number the ultimate responsibility for the choice of the item number rests with the laboratory. Using the guidelines supplied by Medicare, we formulated detailed criteria to classify smears as screening or non-screening, based on the patient's past smear history and/or clinical information provided by the referring doctor. Applying these criteria to cervical smears received in this laboratory in 1993 resulted in 70% being classified as screening and 30% as non-screening smears. Analysis of the cytological predictions for these smears showed substantially higher rates for all grades of abnormalities in the non-screening smears, thus lending support to the validity of our classification system. We conclude that classifying smears into screening and non-screening categories provides valuable information for statistical and quality assurance purposes but can only be useful for monitoring purposes if the criteria for assigning smears are applied consistently by all doctors and laboratories.

Effects of low-dose cyclosporine A on toxicity and rejection in cardiac transplantation.

In conclusion, the low doses of CsA have significantly reduced nephrotoxicity and infectious complications. The patient survival has been acceptable, but there has been a disappointing incidence of rejection and graft loss in patients who have survived the first 3 months. We feel our experience would indicate that by targeting our CsA dosages to such low serum levels some of our patients receive suboptimal immunosuppression. Perhaps the best way of overcoming this is add a third maintenance immunosuppressive agent such as azathioprine to supplement immunosuppression. In fact, we have now changed our immunosuppressive protocol to include azathioprine while maintaining our CsA therapy at its current level.

The Bentall procedure: a surgical option in Ehlers-Danlos syndrome.

The Ehlers-Danlos syndrome (EDs) is one of the most frequently encountered inherited disorders of connective tissue. The arterial-ecchymotic type IV is notorious for large vessel involvement associated with spontaneous catastrophic bleeding. Most of these patients who require cardiovascular surgical procedures have a poor prognosis. Our experience of two patients, with aneurysmal dilatation of the ascending aorta is presented. The first patient presented with an aortic dissection extending from the ascending aorta to the common iliac arteries. The second patient presented with asymptomatic but progressive aneurysmal dilatation of the aortic root. Both patients underwent the Bentall procedure using a 25 mm St. Jude composite valved conduit. Despite increased vascular friability, both of these patients tolerated the operative procedure without complication and are doing well on early follow-up. This experience suggests that the Bentall procedure may be used to decrease the risks of dissection and rupture of the ascending aorta in patients with Ehlers-Danlos syndrome.

Structural features of cell death in atherosclerotic lesions affecting long-term aortocoronary saphenous vein bypass grafts.

Aortocoronary saphenous vein bypass grafts fail because of structural pathologies (thrombosis, intimal hyperplasia and atherosclerosis) within the 'arterialized' vein leading to graft stenosis. This study examined structural characteristics of atherosclerotic alterations in long-term aortocoronary artery saphenous vein bypass grafts with particular attention to the features of cell death in atherosclerotic lesions. Stenotic vein grafts were obtained from 10 patients at redo coronary artery bypass grafting operations. All the grafts were affected by histological abnormalities, with eight out of ten grafts showing evidence of atherosclerotic alterations in the intimal hyperplastic layer. Areas containing foam cells were examined by electron microscopy. Cells with cytoplasmic lipid accumulations were characterized by varying degrees of chromatin condensation, fragmentation or dispersion, by focal areas of oedema and vacuolisation of their cytoplasm, and by plasmalemmal destruction. Some lipid-filled cells exhibiting signs of destruction contained myofilaments and basal membrane fragments, allowing them to be identified as smooth muscle cells. Macrophage foam cells were found to have undergone similar destruction. No cells showing nuclear degeneration were observed to have intact cytoplasmic organelles. Neither were apoptotic bodies identified, but necrotic remnants were frequently seen. The results suggest that cell death in atherosclerotic lesions affecting aortocoronary artery saphenous vein bypass grafts occurs through oncosis rather than by apoptosis.

Electron-microscopic detection of apoptotic and necrotic cell death in non-atherosclerotic areas of stenotic aortocoronary saphenous vein bypass grafts.

Aortocoronary saphenous vein bypass grafts undergo structural alterations within the arterialized vein, resulting in graft stenosis and failure. Areas of the acellular intima contribute to fissuring, cracking and ulceration, while areas of the media become highly vascular but thinned. This study aimed to examine the ultrastructural features of cell death, including apoptosis and necrosis, in non-atherosclerotic areas of the stenotic aortocoronary saphenous vein bypass grafts. Thirteen stenotic vein grafts were obtained at redo coronary artery bypass grafting. The ultrastructural features of cell death were analysed by electron microscopy. Typical features of necrosis, including focal areas of cytoplasmic oedema, plasmalemmal destruction and nuclear condensation with cytoplasmic organelle destruction, were observed throughout the intima and media. Features of apoptosis, including the presence of apoptotic bodies, were also identified in the hyperplastic intima and its adjacent media. Our observations suggest that both apoptosis and necrosis occur in non-atherosclerotic areas of stenotic aortocoronary saphenous vein bypass grafts.